The heart is sometimes incapable of providing sufficient pumping capacity to meet the needs of the body. The effects of this inadequacy can be alleviated by providing a mechanical pump referred to as a mechanical circulatory support device (“MCSD”). An MCSD can be implanted to supplement the pumping action of the heart, most commonly for an extended period of time such as several years.
An MCSD is most commonly connected to the left ventricle. In this arrangement, an inlet end of the pump, or an inlet cannula connected to the inlet end of the pump, is implanted in the wall of the ventricle, such as at the apex of the ventricle. An outlet cannula is connected between the outlet end of the pump and an artery such as the aorta. MCSDs which are connected to a ventricle commonly are referred to as ventricular assist devices or “VADs.” During operation, the VAD assists the heart to pump blood from the left ventricle to the aorta.
The certain MCSDs are typically connected to the heart through the use of a mounting ring, as disclosed in U.S. Published Patent Publication Nos. 2004/0171905, 2007/0134993, and 2015/0112120, the disclosures of which are hereby incorporated by reference herein. A mounting ring has a body and a bore extending through the body, and also has features which can be used to attach the body to the outside of the heart wall so that the bore extends towards and away from the wall. For example, some mounting rings are equipped with a ring of fabric encircling the body, so that the mounting ring can be secured in place by suturing. Other mounting rings are equipped with barbs or other fasteners for attaching the body of the ring to the heart wall. Some mounting rings incorporate an element referred to as a gimbal which is pivotally mounted to the body of the mounting ring and which defines the bore of the mounting ring. The gimbal can be tilted to align the axis of the bore.
A cruciate cut is made in the heart wall within the bore of the mounting ring and a separate surgical tool is used to core a hole in the heart. The pump, or an inlet cannula connected to the pump, is then inserted through the hole into the heart and secured to the mounting ring. If the mounting ring is equipped with a gimbal, the gimbal can be tilted to align the axis of the pump or cannula with the anatomical features of the heart. The seal between the heart and mounting ring must be sufficiently tight to prevent blood loss from the heart. Also, the attachment between the heart and the ring must remain secure despite mechanical stresses and the attachment procedure should minimize damage to the wall of the heart.